This disclosure relates to modular valve assemblies for supplying hydraulic pressure to operate steering, service brakes, a cooling fan, and other functional hydraulic units of a vehicle, including hydraulically operated equipment of the vehicle, for example, a tipping body, for carrying out a work function of the vehicle, and the like.
It is known to provide an articulated dump truck with a main valve assembly formed as a unitary valve block with multiple hydraulic circuits for supplying hydraulic pressure to operate the steering, service brakes and cooling fan, and having hydraulic lines to supply pressure to a second valve assembly located elsewhere on the vehicle. The second valve assembly is configured to control the tipping body or other work equipment of the vehicle responsive to operator commands received at the second valve block.
In such arrangements, it is known to supply pressure to the main valve assembly from two or more pumps, wherein a first one of the pumps supplies the service brake and cooling fan circuits, and a second one of the pumps supplies the steering circuit. A third pump may provide a redundant supply to the steering circuit in parallel with the second pump. The use of two or three separate pumps instead of a single, larger pump makes it easier to fit the pumps into the available space on the chassis of the vehicle, and ensures that adequate flow is available to operate both the service brake and fan circuit and the steering circuit simultaneously at peak demand.
A tipping body or other work equipment of the vehicle will typically be operated when the vehicle is stationary so that the brake and steering functions are not in use, and may require high power or a high flow rate for satisfactory operation when the vehicle is fully loaded. Accordingly, it is known to configure the main valve assembly to combine the supply from both the first and second pumps to power the work equipment via priority valves which prioritise flow to the steering, service brake and fan circuits when required.
It is also known to configure the main valve assembly to supply pressure from the first pump to auxiliary circuits which supply pressure to actuate parking brakes and differential locks of the vehicle. The known main valve assembly is large and complex and is difficult to adapt for use in different vehicles with different equipment specifications. Moreover, its hydraulic efficiency is limited by machining limitations which impose practical constraints on the configuration of the internal flowpaths of the unitary valve block.
In order to provide a more adaptable arrangement, it is known to build a hydraulic valve assembly from modular blocks. By way of example, U.S. Pat. No. 6,325,170 discloses a modular valve assembly supplied from a hydraulic pump. And U.S. Patent Pun. No. 2016/0317956 A1 discloses a tracked mining shovel having a modular valve assembly supplying a plurality of hydraulic circuits from a plurality of hydraulic pumps. The valve assembly includes filter modules, junction modules for combining the flow via two of the filter modules from two of the pumps, and valve modules operable to direct the flow from the junction modules, selectively to actuate either or both of the shovel and the tracks.